Integral prestressed structural concrete column form

ABSTRACT

Apparatus for forming structural concrete members comprising a plurality of mold panels assembled in the desired shape of the structural concrete member and corner bars adapted to engage and hold the mold panels together along longitudinal lines of intersection. The corner bars are preferably rigid angles having lugs extending away from the structural member and being adjustably interconnected tie rods thus enabling the corner bars and panels to produce various size forms, and to be quickly and conveniently set, removed and reused. The principle advantages are derived from the novel corner bars and the manner in which the corner bars are secured together by the members so as to form a lightweight, easily assembled and disassembled structure, yet which is capable of handling heavy, rigorous jobs.

United States Patent [54] INTEGRAL PRESTRESSED STRUCTURAL CONCRETE COLUMN FORM 5 Claims, 7 Drawing Figs.

[52] U.S. Cl 249/48, 249/219 [51] Int. Cl ..'E04g 13/02 a [50] Field of Search 249/48,

[56] References Cited UNITED STATES PATENTS 967,383 8/1910 Hunter 248/222 875,219 12/1910 Scammell 249/48 1,104,651 7/1914 Gagnebin 2,825,116 3/1958 Kenney OTHER REFERENCES MACHINE DESIGN, Sept. 1945. TJl.Ml6. PP. 141- 143.

Primary ExaminerR. Spencer Annear AlromeyG. William King ABSTRACT: Apparatus for forming structural concrete mem bers comprising a plurality of mold panels assembled in the desired shape of the structural concrete member and corner bars adapted to engage and hold the mold panels together along longitudinal lines of intersection. The corner bars are preferably rigid angles having lugs extending away from the structural member and being adjustably interconnected tie rods thus enabling the corner bars and panels to produce various size forms, and to be quickly and conveniently set, removed and reused. The principle advantages are derived from the novel corner bars and the manner in which the corner bars are secured together by the members so as to form a lightweight, easily assembled and disassembled structure, yet which is capable of handling heavy, rigorous jobs.

PATENTEDJUL 6|97l sum 1 0F 2 ANDREW ROBERT HASLETT imam/ ATTORNEY PATENTEB Jul 6 m1 SHEET 2 BF 2 INVENTOR ANDR EW ROBERT HASLETT ATTORNEY INTEGRAL PRESTRESSED STRUCTURAL CONCRETE I COLUMN FORM This invention relates to an apparatus for forming structural concrete members. The invention has particular applicability in .the construction of concrete columns and the following description is made in connection therewith.

' To construct an ordinary concrete column, in a building for example, it is necessary to assemble a mold, usually called a form, position it properly, pour and set concrete,'rem0ve the form and finish the column. The form apparatus employed must be rugged, frequently being exposed to internal pressure of 6,000 p.s.i. or more, and capable of manipulation on the jobsite in a reasonable amountof labor force time with conventional equipment. Current conventionally used column form apparatus is comprised of heavygage, boilerplate steel side panels held together by various comer or side bolting arrangements. The initial cost of these units is very high, they are extremely heavy and difficult to maneuver on the job,'

require substantial assembly and disassembly time .each time they are used, and have limited reusable lives. Other previously known column form apparatusis shown, by way of example in the following U.S. Pat. Nos.: 875,2l9 to Scammell; l,l09,8lto Wilson; 1,104,651 to Gagnebin; and 2,894,312

to Jones.

As will be described,.the present invention hasadvantages and provides improvement ineach of the above-mentioned phases of concrete column construction. The primary object hereof is to provide structural'concrete form apparatus comprised of form panels, novel corner bars positioned at the intersection of the panels with tie means holding the corner bars together. Another more specific object is'to provide novel comer bars for structural concrete form apparatus which are easy to manipulate. In its broadest aspect the invention corner bars are comprised of angle brackets extending for substantially the entire length of structural member, with rearwardly extending lug means provided to connect with lateral tie members.

The form apparatus hereof is adapted to receive the form panel corners directly being contacted and supported throughout substantially all their length by the angle portion of the corner bar while the external lug means of adjacent comer bars are joined together by tie members". 1n the preferred embodiments described hereinafter the lug means extends rearwardly from the side of the angle bracket to provide the tie members with connections spaced from the angle bracket sides. This produces a unique force distribution and structural arrangement resulting in a very strong, rugged, form apparatus held together so as to be conveniently assembled, adjusted to the size desired, readily moved about and positioned on the jobsite, and easily removed from the set concrete and reused.

Other objects and advantages of this invention will be described and will be apparent to those skilled in this art from the appended claims and following detailed description of the preferred mode of carrying out this invention and examples thereof, taken in connection with the accompanying drawings,

wherein:

FIG. 1 is a front elevation view of the preferred embodiment of a column form embodying the principles of this invention;

FIG. 2 is a plan view in section taken along line 2-2 of FIG. 1;

FIG. 3 is a top plan view of the apparatus shown in FIG. 1;

FIG. 4 is a view similar to FIG. 2 but showing a modification;

and

FIGS. 6 and 7 are plan section views of modified forms of the corner bars of the present invention.

Referring to the drawing, the preferred apparatus shown in FIGS. l--3 is comprised of side form panels I0; corner bars indicated generally as tie members '30 and a scaffold in- F IG. 5 is a fragmentary front elevation view of the apparatus of FIG: '4 showing the essential features of the modification;

, '2 dicated generally at 40. The panels may beof any suitable material such as commercially available plywood havinga slickplastic'finished surface facing th'e'concrete column to reduce friction and facilitate removal after the concrete has set. As shown in the drawing the paneling may be of double thickness for large jobs. Chamffer strips 45 .are provided for ornamental purposes. 1

Each corner bar 20 is preferably X-shaped in cross section taken along its longitudinal axis asshown in FIG. 2. It has been found highly advantageous to make the comer bars by extruding from aluminum rather than from heavy steel although any material of suitable strength may be employed. For example, fiberglass canbe used if desired. Also the thickness and length of the angle bracket flanges may be varied depending on the size loads to be encountered. In any case each comer bar is comprised of a corner angle bracket defined by flanges 5 0 and a rearwardly extending lug means comprised of a pair of flanges 60. i a 1 The angle bracket flanges 50 are of sufficient thickness and strength tobe rigid in use. on a column, i.e., capable of withstanding forces set up in use in the concrete form ap parat us. v

Tie members 30 extend through flanges '60 and are threadably engagedtherewith preferably with a backing nut 65 and an external nut 67 on one end and an internally threaded extension rod or turnbuckle 70 on the other end. To apply greater tension to tie member 30 the back nut 65 may be moved inwardly and the outer nut taken up. The same may be done with the extension rod if desired, although the latter is provided primarily to permit length adjustment of the tie members to anydesired length needed between the corner bars depending on the size of the column. I

Each corner bar is adapted to receive a corner or intersection of panels 10 between flanges 50 which extendvertically throughout the length of the column and laterally over a portion of the panels as shown in FlG. 2. Tension adjustably applied in thetie members draws the four corners together to firmly hold panels and corner bars together. The principal advantages of the preferred embodiment result basically from the application or bearing of a continuous angle bracketto the outer surfaces of the panel forms, throughout the length of each intersection to directly contain the panels and concrete without the use of battens or bearing elements interposed between the angle brackets and panels, and in the provision of rearwardly extending lug means connection with lateral tie members. The forces applied by the tie members 30'to the lug flanges 60 create a force distribution which has been found more efficient. Thus the apparatus wherein the tie members are in tension and create a unique force distribution in the corner bars, permits the form assembly to withstand high internal pressure even though the corner bars and panels are made of relatively lightweight materials. As an example of a lightweight unit in actual use for a 10-foot column, 20 by 28 inches, 12-inch tie members spaced 6 inches apart vertically have been employed successfully.

It is desirable to reuse form apparatus as much as possible. It is therefore normal practice to permit the column'to set in a few hours and to remove the form by first loosening the form about the column and then lifting off the column by an overhead crane. This normally permits the contractor to disassemble only a part of the form to avoid time-consuming reassembly for the next column.

By containing the corners of the concrete column as described, within flanges 50 which act as counterstressed bearing elements from the point of intersection of the preferred cross-shape corner bars laterally throughout their width, panels 10 are supported so as to minimize the possibility of deflection or bulging. This is of great advantage in removing and reusing since bulges will restrict the crane from pulling the fonn over thecolumn. Naturally additional finishing is required for bulging places.

The apparatus of this inventionhas advantages in removal and reuse' in that it is lightweight for lifting, item be easily loosened by merely reducing tension in the tie members by the nut arrangement at either end thereof, and bulging is no problem. Further, breaking bolts shown in FIG. 1 (not shown in FIG. 2) are provided in the foot flanges of corner bars 20. After the concrete is set and removal of the form is desired, bolts 80 threadably received in flanges 55 are screwed down against the floor on which the form rests to thereby elevate it slowly and carefully to break with the concrete prior to removal with crane.

At the top of the fonn apparatus shown in FIG. 1 a scaffold is shown comprised of walkway extending around the apparatus and secured in any suitable manner to support a workman without impeding adjustment of tie members 30. A rail 98 is supported from walkway 9S.

FIGS. 4 and 5 illustrate a modification of the invention, eliminating the tie members and substituting another means for holding the corner bars together. A flat steel bar 100 having a series of elongated slots cut in opposite ends thereof, extends between each pair of corner bars. Wedges and 11 l are driven into the slot on opposite sides of each flange 60 which is provided with a slot of slightly larger dimensions than bar 100. The wedges can be raised and lowered and forced tightly against flange 60 to position bar 100 with respect to the comer bars. 3

Although an important feature of the invention is the provision of corner bars of length equal to the column lug flanges extending rearwardly therefrom may be continuous or vertically spaced short dimension lugs ifdesired.

ln FIGS. 6 and 7 two other embodiments are shown to illustrate the scope of this invention, showing two modified cross sections of corner bars. In FIG. 6 lug 110 and extend rearwardly from side flange and but do not extend directly from the latter two flanges. This arrangement provides good force distribution as the tie members are disposed in parallel relationship to flanges 110 and 115, and although this corner bar can be extruded, it is more expensive than the comer bar of FIG. 1.

In FIG. 7 a pair of angle bracket side flanges and are shown having a rearwardly extending lug means which is provided with a lug head having a screw-engaged tie member and a tie member extending therethrough for adjustment. The opposite end of tie member 150 may be adjustably secured in the manner shown for tie member 155. This modification can also be extruded but is less desirable than any of the foregoing embodiments since the resultant force applied to the lug means is directed substantially toward the line of intersection of flanges 130 and 135, but to the extent it provides a continuous angle bracket and accommodates tie members by the rearwardly extending lug means it is within the broader scope of this invention.

Other modifications may be made without departing from the spirit or scope of this invention. For example, the crossshaped comer bars need not form 90 angles in every case since the apparatus is useful in forming other polygonal columns as well as the rectangular one shown in the drawing. The invention may be embodied in still other specific forms without departing from the spirit or scope thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. I

What I claim and desire to be secured by United States Letters Patent is:

l. integral prestressed structural concrete column form means comprising:

a. a plurality of vertically disposed panel means for defining the outer surface of the completed concrete column, each panel means defining an outer surface of the completed column; and

b. clamping means for assembling said plurality of panel means into an integral, prestressed, self-supporting unit, comprisin l. a pluraFity of vertical corner bars, each being an angle bracket extending the length of the completed concrete column and disposed along vertical meeting edges of adjacent panel means to receive'said edges therein, each angle bracket including laterally extending flanges also extending the length of the completed concrete column, each flange being of sufficient thickness and lateral width to be arranged to support and press the panels inwardly of the form to overcome hydrostatic pressure outwardly of concrete poured into the form, thereby preventing bulging of said panel means outwardly during forming of the concrete column;

2. lug means extending rearwardly from each angle bracket and along the entire length thereof; and

3. laterally disposed tie members interconnecting the lug means of adjacent corner bars under tension to press and thereby hold adjacent panel means edges within said angle brackets, each of said tie members being laterally spaced from said panel means to facilitate stripping of at least said corner bars, lug means, and tie members together as an integral unit from the completed concrete column upon completion of the setting of the concrete used to form the column,

said tie means under tension acting through said lug means and consequently said laterally extending flanges to create a bending moment inwardly of the form at an approximate vertical centerline of said panel means to counteract hydrostatic pressure of concrete poured into the form thereby preventing bulging of said panel means outwardly during forming of the concrete column. I

2. Structural concrete form apparatus as defined in claim 1 wherein said corner bars are X-shaped in cross section.

3. Structural concrete form apparatus as defined in claim 1 wherein said corner bars are comprised of lightweight extruded material.

4. Structural concrete form means as defined in claim 1 wherein said lug means is comprised of a lug flange extending rearwardly in right angle relationship from each of said angle bracket laterally extending flanges, and said laterally extending flanges intersect at right angles to each other.

5. Structural concrete form apparatus as defined in claim 1 wherein said tie members are adjustable in length. 

1. Integral prestressed structural concrete column form means comprising: a. a plurality of vertically disposed panel means for defining the outer surface of the completed concrete column, each panel means defining an outer surface of the completed column; and b. clamping means for assembling said plurality of panel means into an integral, prestressed, self-supporting unit, comprising:
 1. a plurality of vertical corner bars, each being an angle bracket extending the length of the completed concrete column and disposed along vertical meeting edges of adjacent panel means to receive said edges therein, each angle bracket including laterally extending flanges also extending the length of the completed concrete column, each flange being of sufficient thickness and lateral width to be arranged to support and press the panels inwardly of the form to overcome hydrostatic pressure outwardly of concrete poured into the form, thereby preventing bulging of said panel means outwardly during forming of the concrete column;
 2. lug means extending rearwardly from each angle bracket and along the entire length thereof; and
 3. laterally disposed tie members interconnecting the lug means of adjacent corner bars under tension to press and thereby hold adjacent panel means edges within said angle brackets, each of said tie members being laterally spaced from said panel means to facilitate stripping of at least said corner bars, lug means, and tie members together as an integral unit from the completed concrete column upon completion of the setting of the concrete used to form the column, said tie means under tension acting through said lug means and consequently said laterally extending flanges to create a bending moment inwardly of the form at an approximate vertical centerline of said panel means to counteract hydrostatic pressure of concrete poured into the form thereby preventing bulging of said panel means outwardly during forming of the concrete column.
 2. lug means extending rearwardly from each angle bracket and along the entire length thereof; and
 2. Structural concrete form apparatus as defined in claim 1 wherein said corner bars are X-shaped in cross section.
 3. Structural concrete form apparatus as defined in claim 1 wherein said corner bars are comprised of lightweight extruded material.
 3. laterally disposed tie members interconnecting the lug means of adjacent corner bars under tension to press and thereby hold adjacent panel means edges within said angle brackets, each of said tie members being laterally spaced from said panel means to facilitate stripping of at least said corner bars, lug means, and tie members together as an integral unit from the completed concrete column upon completion of the setting of the concrete used to form the column, said tie means under tension acting through said lug means and consequently said laterally extending flanges to create a bending moment inwardly of the form at an approximate vertical centerline of said panel means to counteract hydrostatic pressure of concrete poured into the form thereby preventing bulging of said panel means outwardly during forming of the concrete column.
 4. Structural concrete form means as defined in claim 1 wherein said lug means is comprised of a lug flange extending rearwardly in right angle relationship from each of said angle bracket laterally extending flanges, and said laterally extending flanges intersect at right angles to each other.
 5. Structural concrete form apparatus as defined in claim 1 wherein said tie members are adjustable in length. 